In the 4th Generation (4 G) communication system, which is the next generation communication system, intensive research is being conducted to provide users with services having various Qualities-of-Service (QoSs) at a data rate of about 100 Mbps. In particular, a study of the 4 G communication system is now made to support high-speed services in the way of guaranteeing mobility and QoS for a Broadband Wireless Access (BWA) communication system such as wireless Local Area Network (LAN) system and wireless Metropolitan Area Network (MAN) system, and an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system is the typical 4 G communication system.
The IEEE 802.16 communication system is a communication system employing Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) to support a broadband transmission network for physical channels of the wireless MAN system. OFDM/OFDMA transmits multiple subcarriers with orthogonality maintained, making it possible to obtain the optimal transmission efficiency during high-speed data transmission. In addition, OFDM/OFDMA can obtain the optimal transmission efficiency during high-speed data transmission since it has high frequency efficiency and is robust against multi-path fading. As an example of the communication system using OFDMA, there is Wireless Broadband (WiBro), which is 2.3 GHz Portable Internet Service.
In a OFDMA communication system, proper distribution of resources is required to increase channel utilization between a base station (BS) and multiple mobile stations located in a cell. The optimal channel utilization is guaranteed according to the way of channelizing subcarriers, which are kinds of sharable resources, and allocating the subcarriers to the mobile stations in the cell. A set of at least one subcarrier is a subchannel.
Data transmission of the communication system is achieved on a frame-by-frame basis, and each frame is divided into a downlink (DL) data interval capable of transmitting DL bursts and an uplink (UL) data interval capable of transmitting UL bursts. The DL and UL data intervals each are divided in units of slots, each of which is a time-frequency two-dimensional arrangement.
DL bursts occupying multiple time slots are allocated to the DL data interval. Specifically, in the IEEE 802.16 communication system, bursts are generated in the following 3 methods during downlink data burst allocation.
A first method generates one protocol data unit or packet data unit (PDU) [Connection ID (CID)] as one burst, without concatenating multiple PDU[CID]s.
A second method generates one burst by concatenating PDU[CID]s of the same terminal (or mobile station). That is, this method generates one burst by concatenating PDU[CID]s having the same terminal identifier (or Basic Cid (CID)).
A third method generates one burst by concatenating PDU[CID]s having the same Modulation and Coding Scheme (MCS) level. In this case, it does not matter whether the PDU[CID] s are PDU[CID] s of the same terminal, or PDU[CID]s of different terminals.
In the first method and the second method, a MAP size increases with the number of terminals undesirably. In the third method, a size of the data burst that a terminal has received from a base station may increase so that the terminal cannot decode the received data burst.